Taxonomy is the word Drupal uses to talk about categorizing. The tags used on articles in a standard Drupal installation are an example of how Drupal's taxonomy system can be used.

Categories of similar things, such as section tags on articles, are collected into vocabularies. A vocabulary called cities might contain Miami and Mumbai, while a vocabulary called news sections might contain sports, science and politics. In a standard installation, the article tags are collected in a vocabulary simply called tags. Drupal refers to each individual thing in a vocabulary as a term.

It may take a little while before you use these words without getting confused, but it helps knowing them when reading or talking about Drupal. Here is a quick summary for your phrase book:

• Taxonomy is the framework for categorizing—the practice of classifying things.
• A vocabulary is a set of categories, used to separate different kinds of categories. An example vocabulary could be cities.
• Terms are the actual category words, such as Miami or Mumbai. Each term belongs to exactly one vocabulary.

TIP: You will often see the phrase taxonomy term, used to make clear that we're dealing with terms in the Drupal sense, not terms in general. Sometimes the word taxonomy is used as a synonym to vocabulary, which is correct in a more general sense but not the way Drupal uses these words.

The initial version of this section of the Community Documentation came from the book Drupal 7: The Essentials, courtesy of NodeOne and Johan Falk.